Re: [boost] [function] Move constructors and move assignment

Move emulation should be enabled explicity on compilers that don't support rvalue references. This is the way its done with Boost.Unordered which requires defining the BOOST_UNORDERED_USE_MOVE macro. This is because Boost.Move can be break users code on older compilers. See issue #6167 and issue #6311.

No move emulation used in patch #7330. Move semantics enabled only for compilers that really do support rvalues. There is too much workarounds in Boost.Function for old compilers, using Boost.Move will definitely break someones code. -- Best regards, Antony Polukhin